JP2008224232A - Ultrasonic flaw detection device, sensitivity correction method therefor and ultrasonic flaw detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection device for making the measuring sensitivity of a measuring target range substantially constant, a sensitivity correction method of the ultrasonic flaw detection device and an ultrasonic flaw detection method. <P>SOLUTION: The ultrasonic flaw detection device has a plurality of ultrasonic vibrators 111, arranged along the surface of a material to be measured; a waveform memory means 125 capable of a received ultrasonic echo, an arbitrary focal waveform combining part 13 for performing the phase combining of an ultrasonic beam of which the focus is set at an arbitrary position in a measuring range from the content of the waveform memory means 125 and calculating the echo of the ultrasonic beam; and a correction factor operation part 15 for calculating the correction factor multiplied on the echo of an actual material 3 to be measured, on the basis the echo calculated by the arbitrary focal waveform combining part 13 using a material 2 to be measured for correction to store it and a determining part 14 for determining the state of the actual material 3 to be measured, on the basis of the value obtained by multiplying the echo, which is calculated by the arbitrary focal waveform combining part 13, by the correction factor in the measurement of the actual material to be measured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic flaw detector, a sensitivity correction method for the ultrasonic flaw detector, and an ultrasonic flaw detection method. Particularly preferably, the internal state of a material to be measured (a flaw detection material) such as a steel material is super The present invention relates to an ultrasonic flaw detector that uses a sound wave to measure a material to be measured without destroying it, a sensitivity correction method for the ultrasonic flaw detector, and an ultrasonic flaw detector method.

  As a device and a method for measuring a state of a material to be measured such as a steel material, for example, a surface flaw or an internal flaw, an ultrasonic flaw detector and an ultrasonic flaw detection method are widely used. The ultrasonic flaw detector is equipped with an array-type probe (also called an array probe), and changes the phase of the pulse voltage that excites each ultrasonic transducer provided on the array-type probe to measure Some materials allow the ultrasonic beam to move within the material. In the ultrasonic flaw detection method, the ultrasonic wave generated by the ultrasonic transducer of the array probe is propagated inside the material to be measured, and the echo (echo) is detected to detect the surface of the material to be measured and There is a method of measuring abnormal discontinuities existing inside, that is, “scratches (surface and / or internal flaws)”.

  The measurement sensitivity is set to an optimum value in order to measure a flaw existing in a material to be measured using an ultrasonic flaw detector and an ultrasonic flaw detection method and to determine whether or not the measured flaw is a defect. At the same time, it is necessary to perform highly accurate measurement. For this reason, a method of adjusting measurement sensitivity using the bottom echo of the sound part of the material to be measured (sensitivity adjustment method of the bottom echo method) or a method of adjusting measurement sensitivity using a sensitivity standard test piece or a contrast test piece ( Test piece type sensitivity adjustment method) is performed.

  In addition, various sensitivity adjustment methods and sensitivity correction methods, and ultrasonic flaw detectors and flaw detection methods using them have been proposed in order to measure the surface condition and internal condition of the material to be measured with higher accuracy. ing. For example, the following configuration has been proposed as a sensitivity correction method.

  For example, in Patent Document 1, in a sector scanning type ultrasonic flaw detector and ultrasonic flaw detection method, the echo height is made constant (ie, the sensitivity is made constant) by correcting the received signal of the ultrasonic beam. A configuration is disclosed. Specifically, the sensitivity of the received signal is (1) the difference in the deflection angle of the ultrasonic beam due to the difference in the directivity of the probe, and (2) the medium that acoustically couples the probe and the material to be inspected. And (3) attenuation of the ultrasonic beam inside the inspection object and the medium, and (4) difference in beam width at the focal point of the ultrasonic beam. . Therefore, the correction value of the sensitivity change caused by each is calculated and stored by a predetermined mathematical formula, and the sensitivity is corrected based on the stored correction value.

  Further, in Patent Document 2, in a linear scanning ultrasonic diagnostic apparatus, a predetermined signal is added to an echo whose amplitude has changed, thereby canceling the change in the echo and obtaining an echo having a constant amplitude (corrected echo signal). A configuration is disclosed. Specifically, the ultrasonic diagnostic apparatus includes a sensitivity corrector in the depth direction (presumed to be the traveling direction of the ultrasonic beam) and a sensitivity corrector in the azimuth direction (possibly perpendicular to the traveling direction of the ultrasonic beam). With. The azimuth direction sensitivity corrector further includes a plurality of variable resistors and a changeover switch. Then, the signal from each of the resistors is added to the echo reflected from the material to be measured and changed in amplitude in the azimuth direction via the changeover switch. As a result, the echo change is canceled and an echo having a constant amplitude is obtained.

  Thus, an ultrasonic flaw detector using an array probe obtains an echo by propagating an ultrasonic beam to one or more preset focal positions. The conventional sensitivity correction in such an ultrasonic flaw detection apparatus or ultrasonic flaw detection method is to correct changes in sensitivity due to the incident angle of the ultrasonic beam, the beam path length, and the angle of the measurement target part when obtaining an echo. Done.

  However, in the flaw detection method using each of the ultrasonic flaw detection apparatuses, the echo height is different when flaws at the same position on the material to be measured are flawed at the same incident angle and the same beam path. Therefore, the configuration disclosed in each of the above patent documents does not take into account the correction of the difference in sensitivity with respect to the same position.

  By the way, the structure of patent document 3 may be used as a kind of ultrasonic flaw detector and ultrasonic flaw detection method. The ultrasonic flaw detector described in Patent Document 3 is an array type probe capable of emitting an ultrasonic pseudo-plane wave, a waveform memory for storing echoes, and a defect distribution status in a measurement target region from the contents of the waveform memory. Means for calculating.

  According to such a configuration, it is possible to obtain information on the measurement target region over a wide range by one transmission of ultrasonic waves and subsequent reception of ultrasonic waves. By synthesizing a waveform focused at an arbitrary position using the data stored in the waveform memory, highly accurate information can be obtained. Therefore, highly accurate flaw detection can be performed in a short time. Hereinafter, such a flaw detection method may be referred to as a “dynamic focus type flaw detection method”.

  However, when flaw detection is performed using the ultrasonic flaw detector described in Patent Document 3, flaw detection sensitivity may vary depending on the position of a flaw in the measurement target region where the ultrasonic beam is transmitted and received. That is, in the case of the “dynamic focus method” flaw detection method, the detection sensitivity may be different if the setting of the inspection target region is different even though the flaw is at the same position.

Japanese Patent Laid-Open No. 11-183446 Japanese Patent Laid-Open No. 2-246554 JP 2003-28846 A

  In view of the above circumstances, the problem to be solved by the present invention is to measure the surface flaw and / or internal flaw of a material to be measured using an array-type probe in the “dynamic focus method” flaw detection method. Providing an ultrasonic flaw detection apparatus in which the measurement sensitivity of a measurement target range is substantially constant, a sensitivity correction method for the ultrasonic apparatus, and an ultrasonic flaw detection method, for example, surface flaws of substantially the same size and shape existing in a measured material Another object of the present invention is to provide an ultrasonic flaw detector in which the measurement sensitivity of internal flaws is substantially constant, a sensitivity correction method for the ultrasonic device, and an ultrasonic flaw detection method.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a “dynamic focus type” ultrasonic flaw detection apparatus, which includes an array having a plurality of ultrasonic transducers arranged to face the surface of a material to be measured. A probe, a waveform storage unit capable of storing ultrasonic echoes received by each of the ultrasonic transducers as waveform data for each of the ultrasonic transducers, and reading out the contents of the waveform storage unit to make any arbitrary measurement within the measurement range. The phase of the ultrasonic beam whose focal point is located at the position of, and an arbitrary focus waveform synthesizer that calculates the echo of the phase-synthesized ultrasonic beam, and the correction coefficient for multiplying the echo of the actual measured material And a correction coefficient calculation unit to be stored and a state of the actual measured material based on a value obtained by multiplying the echo calculated by the arbitrary waveform synthesis unit in the measurement of the actual measured material by the correction coefficient. It is an Abstract that has a judging section for, a.

  The correction coefficient calculation unit uses a correction target material to be corrected for forming an artificial flaw of a predetermined shape and size at a predetermined depth from the surface with a correction coefficient for multiplying the echo of the actual target material to be measured. It is preferable to calculate and store the echo based on the echo calculated by the arbitrary focal waveform synthesizer.

  Further, the correction coefficient calculation unit includes a combined waveform storage unit that stores an echo of an ultrasonic beam having a focus at a predetermined position calculated by the arbitrary focus waveform combining unit using the measurement target material for correction; Correction coefficient calculation means for calculating a correction coefficient based on an echo stored in the combined waveform storage means and a coefficient for sensitivity adjustment set in advance, and a correction coefficient storage for storing the correction coefficient calculated by the correction coefficient calculation means And means.

  Moreover, it is preferable that the plurality of ultrasonic transducers arranged to face the surface of the material to be measured are arranged in an arc shape or an annular shape.

  The plurality of ultrasonic transducers arranged facing the surface of the material to be measured are grouped into a predetermined number of groups, and the correction coefficient calculation unit calculates and stores a correction coefficient for each group. It is preferable.

  Further, it is preferable to further include a positioning means for the material to be measured for correction.

  In addition, the correction coefficient calculating means synthesizes a phase of an ultrasonic beam whose focal point is located at a predetermined position of the measurement target material for correction using the measurement target material for correction for each group. The echo height of the artificial flaw is calculated from the echo of the synthesized ultrasonic beam, and the depth of the artificial flaw from the surface of the material to be corrected and the echo height of the artificial flaw from the echo height of the artificial flaw It is preferable to estimate a function representing the relationship between the two and calculate a value obtained by multiplying the reciprocal of the estimated function by a coefficient for adjusting sensitivity, and the correction coefficient storage means stores the calculated value as a correction coefficient.

  The present invention also includes a step of grouping a plurality of ultrasonic transducers provided in the array-type probe into a predetermined number of groups, and an artificial flaw having a predetermined shape and size at a predetermined depth from the surface. A step of setting the correction target material to be formed on the ultrasonic flaw detector, and phase-combining an ultrasonic beam whose focal point is located at a predetermined position of the correction target material for each group The step of calculating the echo height of the artificial flaw from the echo of the ultrasonic beam synthesized in phase, and the relationship between the depth of the artificial flaw and the echo height of the artificial flaw based on the calculated echo of the ultrasonic beam A function for estimating the correction coefficient, a correction coefficient obtained by multiplying the reciprocal of the function by a coefficient for adjusting sensitivity, and a step for storing the correction coefficient. It is an effect.

  A step of grouping a plurality of ultrasonic transducers provided in the array-type probe into a predetermined number of groups, and a correction for forming artificial flaws of a predetermined shape and size at a predetermined depth from the surface A step in which a material to be measured is set in the ultrasonic flaw detector, and a phase synthesis of an ultrasonic beam whose focal point is located at a predetermined position of the material to be corrected for each group, and the phase synthesized super Calculating an echo height of the artificial flaw from the echo of the acoustic beam, and estimating a function representing a relationship between the depth of the artificial flaw and the echo height of the artificial flaw based on the calculated echo of the ultrasonic beam The gist of the invention is to include a step and a step of storing a function representing the relationship between the echo heights of the artificial flaws.

  Here, it is preferable that the shape and size of the artificial flaw formed on the correction target material are the minimum shape and size that should be determined as “defects” when they exist in the actual target material.

  In addition, the correction target material is a cylindrical member having a circular cross section, and the artificial flaw is formed at a position half the radius of the correction target material from the center. By rotating the measurement material by 180 °, the echo height of the artificial flaw located at a half depth of the radius from the surface and the echo height of the artificial flaw located at a depth of 3/2 of the radius from the surface are obtained. It is preferable to calculate.

Further, the present invention is a step of comparing the echo height of the flaw existing in the actual measured material and the echo height of the artificial flaw of the stored measured material for correction,
A step of determining a defect existing in the actual material to be measured as a defect when an echo height existing in the actual material to be measured is higher than an echo height of the artificial defect of the stored measurement material to be corrected; The main point is to have.

  According to the present invention, the echo height can be corrected by multiplying the actual echo of the material to be measured by the correction coefficient calculated using the material to be corrected. Therefore, highly accurate measurement can be performed.

  Here, as long as the plurality of ultrasonic transducers provided in the array-type probe are arranged in an arc shape or an annular shape, it is possible to perform highly accurate measurement even on a material to be measured having a substantially circular cross section. it can.

  In addition, a plurality of ultrasonic transducers provided in the array-type probe are grouped into a plurality of groups, and a correction coefficient is calculated for each group, so that measurements can be performed with uniform sensitivity over a wide measurement range. it can. Here, if it is the structure which further has the alignment means of the measured material for correction, the measured material for correction can be automatically aligned at the time of calculating the correction coefficient for each group. It becomes easy.

  Then, the correction means calculates a correction coefficient for each group, and by multiplying the obtained echo in the measurement on the actual material to be measured, the sensitivity difference between the groups can be eliminated or reduced. it can. Therefore, it is possible to perform measurement with uniform accuracy over a wide measurement range.

  Hereinafter, various embodiments and examples of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram schematically showing the configuration of the ultrasonic flaw detector 1a according to the first embodiment of the present invention. The ultrasonic flaw detector 1a according to the first embodiment of the present invention measures the state of a material to be measured by a so-called “dynamic focus method (or sometimes referred to as a volume focus method)”, and an abnormality present in the material to be measured. Such a discontinuous portion can be detected. This “abnormal discontinuity” is referred to as “a flaw (surface flaw and / or internal flaw)” in the present invention. “Flaws” include notches, cracks, bubbles, inclusions and the like.

  The scanning of the “dynamic focus method” is described in Patent Document 3 and will be briefly described below, and detailed description thereof will be omitted.

  In the “dynamic focus method”, an ultrasonic transducer provided in an array probe is excited and its echo is stored, and ultrasonic phase synthesis is performed at an arbitrary position on a computer. Thereby, an ultrasonic beam focused on an arbitrary position is calculated. That is, a plurality of ultrasonic beams with the focus set at an arbitrary position in the measurement target region are calculated by a single transmission / reception of ultrasonic waves. Thereby, it is possible to perform scanning in the array direction of the array-type probe over a wide range of the measurement object by one transmission and reception of ultrasonic waves.

  As shown in FIG. 1, the ultrasonic flaw detector 1a according to the first embodiment of the present invention is arranged so as to face the surface of a material to be measured 3 (or a material to be measured 2 for correction, which will be described later). An array type probe (also referred to as an array probe) 11, a predetermined number of signal processing units 12, an arbitrary focal waveform synthesis unit 13, a determination unit 14, and a correction coefficient calculation unit 15 are provided. .

  The array-type probe 11 includes a predetermined number of ultrasonic transducers 111 that can operate independently. Each ultrasonic transducer 111 is an element capable of transmitting and receiving ultrasonic waves. For example, various known ultrasonic transducers such as quartz and ceramics can be applied.

  These ultrasonic transducers 111 are arranged in series so as to face the surface of the material to be measured 3 (or the material to be measured 2 for correction).

  The array-type probe 11 may be disposed so as to face the material to be measured 3 (or the material to be measured 2 for correction) as described above. In particular, the material to be measured 3 ( Alternatively, it is preferably arranged so as to be along the surface of the correction target material 2).

  For example, as shown in FIG. 1, the material to be measured 3 is a cylindrical member having a substantially circular cross section, and the array probe 11 and the material to be measured 3 are relatively moved in the axial direction of the material to be measured 3 for flaw detection. In this configuration, the array type probe is preferably formed in a substantially arc shape or an annular shape. The ultrasonic transducers 111 are arranged in series according to the shape of the array probe. The material to be measured is set so that the cross-sectional center thereof coincides with the curvature of the array probe 11 or the center of the ring.

  As shown in FIG. 1, when the ultrasonic flaw detector 1a according to the first embodiment of the present invention has an arc-shaped array probe 11, for example, a plurality of arc-shaped array probes. A configuration in which 11 is arranged while being shifted in the axial direction of the material 3 to be measured is applicable. And by setting it as such a structure, it becomes the structure by which the array-type probe 11 (namely, ultrasonic transducer | vibrator 111) surrounds the perimeter of the to-be-measured material 3 as a whole.

  Further, a liquid layer 191 such as water is formed between each ultrasonic transducer 111 and the material to be measured 3, and each ultrasonic transducer 111 and the material to be measured 3 or The correction target material 2 is acoustically coupled. In addition, oils such as machine oil and glycerin can be used as the contact catalyst other than water.

  The signal processing unit 12 includes an ultrasonic pulse transmission / reception timing setting unit 121, an ultrasonic pulse generation unit 122, an ultrasonic echo reception unit 123, an A / D conversion unit 124, and a waveform storage unit 125. The number of signal processing units 12 included in the ultrasonic flaw detector 1 a according to the first embodiment of the present invention is set equal to the number of ultrasonic transducers 111. That is, each ultrasonic transducer 111 has one corresponding signal processing unit 12. Each signal processing unit 12 can operate synchronously and / or independently. In FIG. 1, only one signal processing unit is shown, and the others are omitted.

  The ultrasonic pulse transmission / reception timing setting means 121 can set the timing for exciting each ultrasonic transducer 111 provided in the arrayed probe 11 and can set the reception timing of the ultrasonic echo by each ultrasonic transducer 111. . The ultrasonic pulse generator 122 generates an ultrasonic pulse at the timing set by the ultrasonic pulse transmission / reception timing setting unit 121. And each ultrasonic transducer | vibrator 111 provided in the array-type probe 11 can be excited independently, respectively. The excited ultrasonic transducer 111 transmits ultrasonic waves to the outside (that is, the measurement target material 3 or the correction target measurement material 2).

  Further, each ultrasonic transducer 111 provided in the array probe 11 can receive an ultrasonic echo at the timing set by the ultrasonic pulse transmission / reception timing setting means 121. The ultrasonic echo receiving means 123 can amplify the ultrasonic echo received by each ultrasonic transducer 111. The A / D conversion means 124 can convert the value of the ultrasonic echo received by each ultrasonic transducer 111 and amplified by each ultrasonic echo reception means 123 from an analog value to a digital value. The waveform storage unit 125 can store the value of the ultrasonic echo converted into a digital value by the A / D conversion unit 124.

  And each signal processing part 12 can perform the said operation | movement simultaneously. Each signal processing unit 12 can repeat the above operation in a predetermined short cycle from at least the transmission of the ultrasonic beam to the reception of the ultrasonic echo reflected on the bottom surface of the material 3 to be measured. The waveform storage means 125 of each signal processing unit 12 can accumulate and store at least ultrasonic echoes from the reception of the surface echo to the reception of the bottom echo over time.

  The ultrasonic echoes stored in the waveform storage means 125 of each signal processing unit 12 are sent to the arbitrary focus waveform synthesis unit 13. The arbitrary focal waveform synthesis unit 13 may perform ultrasonic phase synthesis at an arbitrary position in the measurement target region (that is, in the cross section of the measurement target material 3) based on the ultrasonic echo stored in the waveform storage unit 125. it can. That is, it is possible to calculate an ultrasonic beam focused on an arbitrary position in the cross section of the material to be measured 3 and its echo height.

  The determination unit 14 includes a signal correction unit 141, a determination unit 142, and an output unit 143. The signal correction unit 141 corrects the echo height calculated by the arbitrary focal waveform synthesis unit 13 using the correction coefficient calculated by the correction coefficient calculation unit 152 described later. Details of this will be described later. The determination unit 142 determines whether the corrected echo height has a height that exceeds a predetermined threshold value. The output unit 143 outputs the determination result of the determination unit 142.

  The correction coefficient calculation unit 15 includes a combined waveform storage unit 151, a correction coefficient calculation unit 152, and a correction coefficient storage unit 153. The combined waveform storage unit 151 can store the echo height calculated in the arbitrary focus combining unit. The correction coefficient calculation unit 152 can read the contents of the combined waveform storage unit 151 and calculate the correction coefficient. The correction coefficient storage unit 153 can store the correction coefficient calculated by the correction coefficient calculation unit 152 in an accumulative manner.

  The processing executed in the sensitivity correction method of the ultrasonic flaw detector 1a according to the first embodiment of the present invention is as follows.

  First, the outline will be described.

  In the sensitivity correction method of the ultrasonic flaw detector 1a according to the first embodiment of the present invention, a plurality of ultrasonic transducers 111 provided in the array probe 11 are divided into a predetermined number of groups, and each group is divided into groups. A process of calculating a correction coefficient is included (transmission of ultrasonic waves is performed simultaneously by all groups). The calculated correction coefficient is a coefficient to be multiplied by the echo height value calculated by the arbitrary focal waveform synthesizer 13 in the measurement of the actual device under test 3 (for example, measurement of the product before shipment). By multiplying the value of the echo height calculated by the arbitrary focal waveform synthesizer 13 by the correction coefficient, the value of the echo height is corrected, and the measurement sensitivity becomes equal among the groups of the ultrasonic transducers 111.

  The calculation of the correction coefficient is performed based on the echo height calculated using the measurement target material 2 for correction as the measurement object. The material to be measured 2 for correction is a member having substantially the same cross-sectional shape and dimensions as the material to be measured 3 (for example, a product before shipment) for actual measurement. An artificial flaw 21 having a predetermined shape and size (both known) is formed at a predetermined known position in the cross section.

  When calculating the echo height of the artificial flaw 21 for each group of the ultrasonic transducers 111, if the relative positional relationship between the group of the ultrasonic transducers 111 and the artificial flaw 21 is made equal, the obtained echo is an ultrasonic wave. There should be no difference between groups of transducers 111. However, actually, the echo height of the obtained artificial flaw 21 may be different for each group of the ultrasonic transducers 111 (in other words, a difference occurs between the groups of the ultrasonic transducers 111). Therefore, the ultrasonic flaw detector 1a according to the first embodiment of the present invention calculates and stores a correction coefficient based on the echo height of the artificial flaw obtained for each group in order to correct the sensitivity.

  Then, in actual measurement (flaw detection for a product to be shipped), the obtained echo height is multiplied by the correction coefficient obtained as described above. Based on the echo height multiplied by this correction coefficient, the internal state of the material to be measured 3 is measured. In this way, the reception sensitivities after correction of each group are substantially equal to each other, so that the measurement accuracy of the ultrasonic flaw detector 1a according to the first embodiment is improved.

  Next, with reference to FIG. 2 and FIG. 3, the sensitivity correction method of the ultrasonic flaw detector 1a according to the first embodiment of the present invention, that is, the ultrasonic flaw detector 1a when calculating and storing the correction coefficient. The operation will be described in detail. FIG. 2 is a flowchart showing a sensitivity correction method of the ultrasonic flaw detector 1a according to the first embodiment of the present invention. FIG. 3 shows each group 112 of the ultrasonic transducers 111 provided in the array-type probe 11 and the ultrasonic beam U synthesized in each group 112 when the sensitivity correction method is performed. It is sectional drawing which showed typically the relationship with the artificial flaw 21 formed in the to-be-measured material 2 for correction | amendment.

  In step S <b> 1, a plurality of ultrasonic transducers 111 provided in the array probe 11 are grouped into a predetermined number of groups 112. In this grouping, the same number of consecutive ultrasonic transducers 111 among the ultrasonic transducers 111 arranged in series on the array-type probe 11 are set as one group 112.

  For example, among the plurality of ultrasonic transducers 111 arranged in series on the array-type probe 11, the first to tenth ultrasonic transducers 111 from one end of the array-type probe 11 are connected to the first group, The 11th to 20th ultrasonic transducers 111 are the second group, the 21st to 30th ultrasonic transducers 111 are the third group, the 31st to 40th ultrasonic transducers 111 are the fourth group,...・ Grouped as such.

  The grouping of the ultrasonic transducers 111 is not limited to a method in which one specific ultrasonic transducer 111 belongs to one specific group 112. That is, a grouping method in which one ultrasonic transducer 111 belongs to a plurality of groups 112 may be used.

  Specifically, for example, among the plurality of ultrasonic transducers 111 provided in the array-type probe 11, the first to tenth ultrasonic transducers 111 from one end of the array-type probe 11 are connected to the first group, The 6th to 15th ultrasonic transducers 111 are the second group, the 11th to 20th ultrasonic transducers 111 are the third group, the 16th to 25th are the fourth group, and so on. A grouping method may be used.

  The number of ultrasonic transducers 111 belonging to each group 112 is preferably set equal to each other. However, the number of ultrasonic transducers 111 belonging to one group 112 is not specifically limited. Similarly, the number of groups 112 is not limited (FIG. 3 shows a configuration including four groups of ultrasonic transducers 111, but is not limited to this configuration). What is necessary is just to set suitably according to the number etc. of the ultrasonic transducer | vibrator 111 provided in the array type probe 11. FIG.

  In step S2, the correction target material 2 used in the sensitivity correction method of the ultrasonic flaw detector 1a according to the first embodiment of the present invention is used as the ultrasonic flaw detector 1a according to the first embodiment of the present invention. It is set. As described above, the material to be measured 2 for correction has substantially the same cross-sectional shape and dimensions as the material 3 to be measured (for example, a product before shipment) that is actually measured. An artificial flaw 21 having a predetermined shape and a predetermined size is formed at a predetermined position in the cross section. As this artificial flaw 21, a round hole having a predetermined diameter can be applied.

  The position of the artificial flaw 21 is determined based on the depth from the surface of the correction target material 2 to which the ultrasonic beam is transmitted and the arrangement direction of the ultrasonic transducers 111 of the array-type probe 11 (that is, ultrasonic waves). And the direction in which the groups 112 of the vibrators 111 are arranged). When the correction target material 2 has a substantially circular cross section, the position of the artificial flaw 21 is specified by the depth from the surface (or the distance from the center) and the circumferential position.

  If the ultrasonic flaw detector 1a according to the first embodiment of the present invention has the array-type probe 11 formed in an arc shape or an annular shape and measures the cylindrical measuring material 3, the correction flaw is used. The material to be measured 2 is set so that the cross-sectional center thereof substantially coincides with the center of curvature of the array probe 11. In addition, if the array-type probe 11 formed in a straight line is used to measure the prism-shaped material 3 to be measured, the correction target material 2 is connected to the array-type probe 11. The opposing surfaces are set so as to be substantially parallel to the array-type probe 11.

  In step S3, alignment of the correction target material 2 is performed. That is, the specific one group 112 of the ultrasonic transducer 111 for which the correction coefficient is calculated in step S3 and the artificial flaw 21 formed on the correction target material 2 are in a predetermined positional relationship. The measurement target material 2 for correction is moved and / or rotated.

  For example, among the ultrasonic beams synthesized by the specific group 112 of the ultrasonic transducer 111 for calculating the correction coefficient, the ultrasonic beam U whose focal point is located at a predetermined position, here, the measurement target material for correction Artificial flaw 21 formed on the correction target material 2 on the central axis of the ultrasonic beam U whose focal point is located on the bottom surface of 2 (the surface opposite to the surface on which the ultrasonic beam is transmitted). Alignment is performed so that is positioned (see FIG. 3).

  Specifically, it is as follows. The echo height of the artificial flaw 21 is the highest when the artificial flaw 21 is located on the central axis of the ultrasonic beam U emitted from the specific group 112 of the ultrasonic transducer 111 for which the correction coefficient is calculated. It is thought that it gets smaller as it goes off.

  Therefore, after the correction target material 2 is set in the ultrasonic flaw detector 1a according to the first embodiment of the present invention by rough positioning (or even if rough positioning is not required), the alignment means 17 is provided. Then, the measurement target material 2 for correction is moved and / or rotated. In step S3, the position where the echo height of the artificial flaw 21 received by one specific group 112 of the ultrasonic transducer 111 for which the correction coefficient is calculated is highest is found.

  Specifically, the position at which the echo height of the artificial flaw 21 is highest is obtained by alternately repeating the movement and / or rotation of the correction target material 2 and the measurement of the echo height of the artificial flaw 21. Find out. At the position where the echo height of the artificial flaw 21 is the highest, the artificial flaw 21 formed on the correction target material 2 is synthesized by a specific group 112 of the ultrasonic transducer 111 for calculating the correction coefficient. It should be located on the central axis of the acoustic beam U.

  Although the correction target material 3 is described as “rotation”, actually, the correction of the correction target material 2 is not performed by alternately rotating in both forward and reverse directions instead of rotating in one direction. Positioning is done. The same applies to “movement”, and the measurement target material 2 for correction is positioned by repeating bidirectional movement instead of movement in one direction.

  When the array-type probe 11 of the ultrasonic flaw detector 1a according to the first embodiment of the present invention is formed in an arc shape or an annular shape, and the cross-sectional shape of the correction target material 2 is substantially circular, correction is performed. The alignment of the measurement target material 2 may be performed by rotating the center of the cross section about the center of rotation to satisfy the positional relationship (see FIG. 3). Rotate it).

  From step 4 to step 7, measurement by the dynamic focus method is executed for each group 112 of the ultrasonic transducer 111.

  Specifically, in step 4, the ultrasonic transducers 111 belonging to all the groups 112 emit an ultrasonic beam and receive the echo. Next, in step 5, the echo received by the ultrasonic transducer 111 is amplified by the ultrasonic echo receiving means 123, the amplified echo is converted into a digital value by the A / D conversion means 124, and the converted value is stored in the waveform. Means 125 stores.

  In step 6, the arbitrary focus waveform synthesis unit 13 reads the echo value stored in the waveform storage means of the signal processing unit 12. For the ultrasonic transducers 111 in the group 112 for calculating the correction coefficient, waveform data such that the bottom surface of the correction target measurement material 2 (the surface opposite to the surface facing the ultrasonic transducer 111) is in focus. (Refer to the shape of the ultrasonic beam U in FIG. 3), and an ultrasonic echo having such a waveform is calculated. In step 7, the combined waveform storage unit 151 of the correction coefficient calculation unit 15 stores the echo calculated by the arbitrary focus waveform combining unit 13.

  The above operations from Step 3 to Step 7 are executed for all other groups 112 of the ultrasonic transducers 111 (Step 8). That is, transmission of ultrasonic beams by all groups 112, alignment of the measurement target material 2 for correction, and calculation of ultrasonic beams whose focal points are located at predetermined positions and their echoes for each specific group 112; repeat.

  The echoes calculated by the arbitrary focus waveform synthesis unit 13 for each group 112 are stored in the synthesized waveform storage unit 151 of the correction coefficient calculation unit 15 in an accumulative manner. Therefore, when the operation from step 3 to step 7 is completed for all the groups 112 of the ultrasonic transducer 111, all the groups 112 of the ultrasonic transducer 111 are stored in the combined waveform storage unit 151 of the correction coefficient calculation unit 15. Therefore, the echoes of the artificial flaws 21 having the same relative positional relationship with each other are stored.

  Note that the alignment (step 3) of the artificial flaws of each group 112 may differ depending on the shape of the array probe 11 and the cross-sectional shape of the correction target material 2 to be measured.

  For example, as shown in FIG. 3, when the array-type probe 11 has an arc shape or an annular shape and the cross-sectional shape of the correction target material 2 is substantially circular, the correction target material 2 is The rotation can be performed by a predetermined angle with the center of the cross section as the center of rotation (the arrow in the figure indicates the direction of rotation). On the other hand, when the array-type probe 11 is formed in a straight line and the cross-sectional shape of the correction target material 2 is a substantially quadrilateral, the correction target material 2 and / or the array-type probe. 11 can be performed by relatively moving a predetermined distance in the arrangement direction of the group 112 of the ultrasonic transducers 111.

  In addition to this, there is a method in which a plurality of correction materials 2 to be corrected at different positions where the artificial flaws 21 are formed are prepared and exchanged for each group 112 of the ultrasonic transducer 111 to store the echoes of the artificial flaws 21. There may be. That is, a plurality of materials to be measured for correction having the same shape, size, and depth position from the surface of the artificial flaw 21 and different positions in the array direction of the ultrasonic transducers 111 provided in the array probe 11 are used. 2 is prepared.

  And when transmitting an ultrasonic beam and memorize | storing an echo, it replaces | exchanges for the to-be-measured material 2 for a predetermined correction | amendment for every group 112. FIG. In such a method, the operation from step S2 to step S7 is performed for each group 112 of the ultrasonic transducer 111. That is, in FIG. 2, if “No” in step S8, the route of the broken line is followed instead of the solid line, and the process returns to step S2.

  Note that the above method can also be applied when the shape of the array-type probe 11 is other than an arc shape, an annular shape or a linear shape, and the cross-sectional shape of the correction target material 2 is other than a substantially circular shape or a substantially quadrilateral shape. That is, a different measurement target material 2 for correction is prepared for each group 112 of ultrasonic transducers 111 that stores echoes. Then, for the specific group 112 of the ultrasonic transducer 111, when performing the operations from step 2 to step 7, a method of replacing the measured material 2 for a predetermined correction in step 2 can be applied.

  Next, the correction target material 2 having different depths of the artificial flaws 21 is used, and the correction target material 2 having the artificial flaws 21 having different depths is echoed for each group 112 of the ultrasonic transducer 111. Is calculated. The calculated echo is stored accumulatively in the combined waveform storage means 151 of the correction coefficient calculator 15. That is, the operation from step 2 or step 3 to step 7 is executed for each group 112 of the ultrasonic transducer 111 for the correction target material 2 in which the artificial flaw 21 is formed at different depth positions.

  The type and number of depths from the surface of the artificial flaw 21 are not limited. However, it is possible to calculate a highly accurate correction coefficient by calculating echoes for many types of depths.

  When calculating the echoes of the artificial flaws 21 having different depths, a plurality of correction target materials 2 having different depths from the surface of the artificial flaws 21 are prepared, and the echoes are calculated by appropriately replacing them. The method is applicable. However, by using the following method, the types of depth of the artificial flaw 21 can be increased without increasing the types of the measurement target material 2 for correction.

  When the array-type probe 11 is formed in a substantially arc shape or a substantially annular shape and the cross-sectional shape of the correction target material 2 is substantially circular, the correction target material 2 is rotated by 180 °. The depth position of the artificial flaw 21 can be changed. For example, if the correction target material 2 has a radius R and the distance from the center of the artificial flaw 21 is r, the correction target material 2 is rotated 180 degrees from the surface (R Echoes can be calculated for the artificial flaw 21 at a depth of -r) and the artificial flaw 21 at a depth of (R + r) from the surface.

  On the other hand, when the array-type probe 11 is formed in a substantially linear shape and the cross-sectional shape of the correction target measurement material 2 is a substantially quadrangular shape, an ultrasonic beam is first transmitted to one surface of the artificial flaw 21. Calculate the echo. Thereafter, the front and back of the correction target material 2 are exchanged and an ultrasonic beam is transmitted / received to the other surface to calculate the echo of the same artificial flaw 21. For example, when the thickness dimension of the correction target material 2 is H and the depth dimension from one surface of the artificial flaw 21 is h, the single correction target material 2 is used. The echoes of the artificial flaw 21 at the depth h from the surface and the same artificial flaw at the depth (Hh) from the surface can be calculated.

  Then, the echoes of the artificial flaws 21 having all the predetermined depths are calculated and stored for all the groups 112 of the ultrasonic transducer 111 (step S9). Note that when the depth of the artificial flaw 21 is changed, if the correction target material 2 needs to be changed (replaced), the process returns to step S2 along the path indicated by the broken line. As a result, the echoes of the artificial flaws 21 existing at the respective depths for all the groups 112 are accumulated in the combined waveform storage unit 151 of the correction coefficient calculation unit 15.

  Next, in step S <b> 10, the correction coefficient calculation means 152 of the correction coefficient calculation unit 15 calculates the correction coefficient for each group 112 of the ultrasonic transducer 111. In step S11, the correction coefficient storage unit 153 of the correction coefficient calculation unit 15 stores the calculated correction coefficient. This operation (calculation and storage of correction coefficient) is performed for all groups 112 of the ultrasonic transducer 111 (step S12).

  A specific method for calculating the correction coefficient is as follows.

  First, the relationship between the depth from the surface of the material to be measured 2 for correction to which the ultrasonic beam is transmitted, or the time after transmitting the ultrasonic beam, and the calculated echo height of the artificial flaw 21 Is estimated. Specifically, for example, the depth from the surface of the material to be measured 2 for correction to which the ultrasonic beam is transmitted, or the time after transmitting the ultrasonic beam is defined as the domain (x-axis) and calculated. A graph is created with the echo height of the generated artificial flaw 21 as the range (y-axis).

A straight line or curve indicating the relationship between the depth or time and the echo height, that is, the function y = F _i (x) is estimated from the created graph. Here, x is the depth from the surface of the correction target material 2 on which the ultrasonic beam is transmitted, or the time since the ultrasonic beam is transmitted, and y is the echo height of the artificial flaw 21. That's it. Note that the suffix i of each function indicates a group of the ultrasonic transducer 111 (that is, indicates a function for the i-th group).

The method for estimating the function is not limited to a specific method as long as an appropriate method is selected according to the plot of the obtained graph. For example, various known methods such as a least square method can be applied. Further, the type of function to be estimated is not limited. In the present invention, the function F _i (x) thus estimated is referred to as a “correction function”. These correction functions F _i (x) may be different for each group 112 of the ultrasonic transducer 111.

Then, when the correction function has the F _i (x), defining the function G _i (x) of _{G i (x) = a /} F i (x). The coefficient a is a coefficient for adjusting the echo height after correction, and its value is arbitrarily set. However, it is usually set in a range exceeding 0 and less than 1, and preferably in a range of 0.7 to 0.8. Here, this coefficient a is referred to as a “sensitivity coefficient”.

Then, the value of G _i (x) is calculated at a predetermined numerical interval with respect to the actual depth from the surface to the bottom surface of the measured material 3 and stored in the correction coefficient storage means 153. A specific value of the calculated G _i (x) is a correction coefficient for the sensitivity of the depth x of the ultrasonic elements belonging to the group 112.

  When the correction coefficient calculated in this way is multiplied by the echo height calculated in the actual measurement, the sensitivity between the groups 112 becomes substantially equal, and as a result, highly accurate flaw detection can be performed. The reason is as follows.

The correction function F _i (x) is a function representing the relationship between the depth from the surface of the correction target material 2 and the echo height of the artificial flaw 21 having a predetermined shape and size. Therefore, when the echo height calculated using the correction target material 2 is multiplied by the inverse 1 / F _i (x) of the value of the correction function F _i (x), the group 112 of the ultrasonic transducers 111 and Regardless of the depth from the surface of the material to be measured 2 for correction, the value is almost 1. That is, by multiplying the echo height by 1 / F _i (x), the sensitivity difference between the groups 112 and the influence of the depth from the surface are removed.

  Further, when the sensitivity coefficient a is further multiplied, the value does not depend on the depth from the surface of the group 112 of the ultrasonic transducer 111 and the measurement target material 2 for correction, and the echo height of the artificial flaw 21 is the transmitted super This is approximately (a × 100)% of the sound beam.

  Since the shape and dimensions of the artificial flaw 21 formed on the correction target material 2 are already known, based on the value obtained by multiplying the echo height calculated using the actual target material 3 by the correction coefficient, It is possible to estimate the size of a flaw existing in the material 3 to be measured. At least, it is possible to determine whether a flaw present in the actual measurement target material 3 is larger or smaller than an artificial flaw 21 formed in the correction target measurement material 2. That is, if the value of the echo height multiplied by the correction coefficient is higher than (a × 100)%, the flaw is larger than the artificial flaw 21 of the correction target material 2 and smaller if it is lower.

  According to such a method, if the dimensions and shapes of the flaws are substantially equal, a substantially constant echo height can be obtained regardless of the position (depth from the surface). That is, the sensitivity can be made constant. When such correction is performed for all the groups 112, the sensitivity difference between the groups 112 is eliminated or reduced, and the entire measurement target range can be measured with high accuracy.

  Next, the operation at the time of flaw detection of the ultrasonic flaw detector 1a according to the first embodiment of the present invention will be described. The material to be measured 3 is a columnar member, and flaw detection is performed while moving in the axial direction.

  A description will be given with reference to FIG. First, the ultrasonic pulse transmission / reception timing setting means 121 generates a pulse transmission timing signal and transmits it to the ultrasonic pulse generation means 122. The ultrasonic pulse generating means 122 receives this signal and sends a spike pulse simultaneously to the ultrasonic transducers 111 provided in the array probe 11. Thereby, each ultrasonic transducer | vibrator 111 is excited simultaneously and an ultrasonic wave is emitted. The envelope of the ultrasonic wave emitted from each ultrasonic transducer 111 is substantially equal to the array shape of the ultrasonic transducers 111 in the array probe 11. That is, when the ultrasonic probe 11 is formed in an arc shape or an annular shape, the envelope of each ultrasonic wave is a concentric circular arc shape or an annular shape. When the array probe 11 is formed in a substantially straight line, the envelope becomes a substantially straight line, and the ultrasonic wave becomes a pseudo plane wave.

  The emitted ultrasonic wave propagates through the liquid layer 191 and is partially reflected at the boundary between the liquid layer 191 and the material 3 to be measured. Then, when the ultrasonic wave propagated inside the material to be measured 3 encounters an acoustic reflection surface such as a flaw existing inside the material to be measured 3, a part of the ultrasonic wave is reflected there. Furthermore, the ultrasonic waves that reach the opposite surface of the material to be measured are reflected there.

  Each ultrasonic transducer 111 receives a surface echo, an echo on the acoustic reflection surface, and a bottom surface echo. The ultrasonic echo receiving unit 123 amplifies the received ultrasonic echo, and the A / D conversion unit 124 converts the amplified ultrasonic echo from an analog value to a digital value. The waveform storage unit 125 stores the ultrasonic echo converted into the digital value together with the position in the depth direction of the material 3 to be measured and the position in the arrangement direction of the ultrasonic transducer 111. Alternatively, it is stored in a predetermined address corresponding to the depth direction of the measurement target material 3 and the arrangement direction of the ultrasonic transducers 111.

  The arbitrary focus waveform synthesizing unit 13 reads the ultrasonic echo stored in the waveform storage unit 125 in the depth direction of the material 3 to be measured and the arrangement direction of the ultrasonic transducer 111 while using the dynamic focus method (according to the dynamic focus method). For details of the scanning method, refer to Patent Document 3). The signal correction unit 141 multiplies the value of the scanning result by the dynamic focus method by the correction coefficient calculated as described above. As a result, if the flaws existing in the material to be measured 3 have the same size, the material to be measured 3 has a substantially constant sensitivity regardless of the arrangement direction of the ultrasonic transducers 111 of the array probe 11. The state can be measured.

  The determination unit 142 determines whether or not the ultrasonic echo is a defect based on the scanning result multiplied by the correction coefficient. That is, if the echo height is greater than or equal to a predetermined value, it is determined that the flaw is a defect. The output unit 143 outputs the determination result by the determination unit 142.

  Next, a second embodiment of the present invention will be described. The second embodiment of the present invention has a configuration that is particularly suitable for measuring a material to be measured having a substantially circular cross section. FIG. 4 is a block diagram schematically showing the configuration of the ultrasonic flaw detector 1b according to the second embodiment of the present invention. In addition, about the same structure as the ultrasonic flaw detector 1a concerning 1st embodiment of this invention, the same code | symbol is attached | subjected and shown, and description is abbreviate | omitted.

  The ultrasonic flaw detector 1b according to the second embodiment of the present invention includes, in addition to the configuration of the ultrasonic flaw detector 1a according to the first embodiment, a control means 16 and an alignment means for the correction target material 2 to be measured. Have The control unit 16 controls the alignment unit 17 of the correction target material 2 and the ultrasonic pulse transmission / reception timing setting unit 121. The alignment means 17 of the correction target material 2 is controlled by the control means 16. According to such a configuration, when the correction coefficient is calculated, the position of the artificial flaw 21 of the correction target material 2 set in the ultrasonic flaw detector 1b according to the second embodiment is automatically performed. be able to.

  FIG. 5 is a plan view schematically showing a first example of the configuration of the positioning means 17 of the correction target material 2 to be measured. 5 (a) and 5 (b) are a front view and a side view of the ultrasonic flaw detector 1b showing a state in which the actual object 3 is being measured, and FIGS. 5 (c) and 5 (d) are correction coefficients. It is the front view and side view of the ultrasonic flaw detector 1b which showed the state which is calculating. As shown in FIG. 5, the alignment means 17 a according to the first example includes a cylinder 171, a piston 172 that can reciprocate the cylinder, and a rotating roller 173 provided near the tip of the piston 172.

  Various known cylinders such as a hydraulic cylinder can be applied to the cylinder 171. The piston 172 can reciprocate in the axial direction of the cylinder 171 by the fluid in the cylinder 171. The cylinder 171 and the piston 172 are provided such that their axes intersect with the direction of the axis of the material to be measured 3 at substantially right angles. The rotating roller 173 is configured to be rotatable by a rotational power source (not shown) provided inside or outside. The rotating shaft of the rotating roller 173 is set substantially parallel to the axial direction of the material 3 to be measured. A plurality of positioning means 17 a are arranged so as to surround the material to be measured 3. FIG. 5 shows a configuration in which three sets of alignment means 17a are provided. The operations of the cylinder 171, the piston 172, and the rotating roller 173 are controlled by the control means 16.

  The operation of the positioning means 17a is as follows.

  As shown in FIGS. 5A and 5B, the ultrasonic flaw detector 1b according to the second embodiment rotates while the actual measurement target material 3 (for example, a product before shipment) is flaw-detected. The roller 173 is maintained in a state not in contact with the material 3 to be measured. The material to be measured 3 is measured while being conveyed by the conveying roller 192.

  As shown in FIGS. 5C and 5D, when performing sensitivity correction, first, the correction target material 2 is set in the ultrasonic flaw detector 1b according to the second embodiment. Then, the control means 16 advances the piston 172 to bring the rotating roller 173 into contact with the measurement target material 2 for correction. As a result, the correction target material 2 is held by each rotating roller. Then, the control means 16 automatically aligns the artificial flaw 21 by rotating the rotating roller in the alignment of the artificial flaw 21 (see step S3 in FIG. 2).

  FIG. 6 is a plan view schematically showing a second example of the configuration of the alignment means for the correction target material 2 to be measured. As shown in FIG. 6, the alignment means 17 b according to the second example includes a rotational power source 174 and a holding unit 175. The rotational power source 174 can rotate the measurement target material 2 for correction. For example, various known electric motors and hydraulic motors can be applied. The rotational power source 174 is controlled by the control means 16. The holding part 175 is a part for holding (for example, fixing) the rotational power source 174 to the ultrasonic flaw detector 1b, and its configuration is not limited.

  The operation of the positioning means 17b is as follows.

  While the ultrasonic flaw detector 1b according to the second embodiment is performing flaw detection on an actual measurement target material 3 (for example, a product before shipment), the positioning means 17b is removed from the ultrasonic flaw detector 1b. Is in a state. When performing sensitivity correction, first, the correction target material 2 is set in the ultrasonic flaw detector 1b according to the second embodiment. Specifically, each holding unit 175 is held by the transport roller 192. Further, the rotational power source 174 is coupled to the correction target material 2. As a result, the correction target material 2 is rotated by the rotational power source 174. Then, the control means 16 automatically aligns the artificial flaw 21 by rotating the rotating roller in the alignment of the artificial flaw 21 (see step S3 in FIG. 2).

  Next, a third embodiment of the present invention will be described.

In the first and second embodiments, after estimating the correction function F _i (x), the sensitivity between the groups 112 is made uniform by defining Gi (x) = a / F _i (x). It is a correction. On the other hand, the third embodiment uses the value of the correction function F _i (x) as it is as the threshold value of the determination unit 142, thereby determining whether or not the “flaw” existing in the actual measured material 3 is “defect”. It is the structure which determines.

That is, the artificial flaw of the measurement target material 2c for correction is formed in a minimum size when determining as a “defect” of the product. Then, the correction function F _i (x) is estimated using the correction target material 2c. The method for estimating the correction function F _i (x) can be the same as that in the first embodiment or the second embodiment. Therefore, the description is omitted.

The correction coefficient storage unit 153, together with specific values of Gi (x) = in place of the specific value of a / F _i (x) (Note, Gi (x) = a / F i (x) A specific value of the correction function F _i (x) may be stored. As described above, the shape and size of the artificial flaw of the measurement target material 2c for correction are formed to have a minimum size when determining as a “defect” of the product, and thus a specific correction function in the third embodiment. The numerical value of F _i (x) is a threshold value indicating whether or not “defects” in the material to be measured are “defects”. Alternatively, the value of the correction function F _i (x) may be multiplied by a so that the shape and dimensions of the artificial flaw 21 formed on the correction target material 2 are determined at a different level.

Thereafter, the actual measurement object 3 is flawed. When the echo height received and calculated by each group 112 is smaller than a specific value of the correction function F _i (x) for the group 112, the detected “flaw” is “defect”. If it is not judged and is large, it is judged as “defect”. Even with such a configuration, it is possible to perform high-accuracy flaw detection for each group 112, and for example, it is possible to prevent or suppress missing “flaws” that should be determined as “defects”.

  Next, examples of the present invention will be described.

  The ultrasonic flaw detector according to the embodiment of the present invention has a configuration capable of measuring a columnar or cylindrical material to be measured having a substantially circular cross section. Specifically, it has three sets of array-type probes 11 formed in an arc shape along the surface of the material to be measured 3, and these three sets of array-type probes 11 are made of the material to be measured. It arrange | positions so that the perimeter may be surrounded. Each arrayed probe 11 is arranged so as to be shifted in the axial direction of the material 3 to be measured. Each array-type probe 11 includes 128 ultrasonic transducers 111.

  In the embodiment of the present invention, the first correction target material 2a and the second correction target material 2b are used. The first material to be measured 2a for correction is a cylinder of SCM435 and φ46mm. Then, a hole of φ0.3 mm is formed as an artificial flaw 21 at a position at a distance of half the radius from the center. The second material to be measured 2b for correction is a cylinder with a material of S25C and φ46 mm. A hole with a diameter of 0.3 mm is formed as an artificial flaw 21 at the approximate center of the cross section.

  Hereinafter, based on FIG. 2 etc., the procedure of the correction | amendment method of the ultrasonic flaw detector which concerns on the Example of this invention is demonstrated.

  Referring to FIG. 2, in step S1, the ultrasonic transducers 111 provided in each array probe 11 are grouped. In the present embodiment, among 128 ultrasonic transducers 111 arranged in series on each array probe 11, the first to 32nd ultrasonic waves from one end are the first group, and the 17th to 48th ultrasonic waves. The transducer 111 is the second group, the 33rd to 64th ultrasonic transducers 111 are the third group, the 49th to 80th ultrasonic transducers 111 are the fourth group, and the 65th to 96th ultrasonic transducers. 111 is a fifth group, the 81st to 112th ultrasonic transducers 111 are a sixth group, and the 97th to 128th ultrasonic transducers 111 are a seventh group.

  In step S2, the first material to be measured 2a for correction is set in the ultrasonic flaw detector according to the embodiment of the present invention, and alignment is executed in step S3. Specifically, the artificial flaw 21 formed on the first correction target material 2a is on the center line of the ultrasonic beam synthesized by the second group of the ultrasonic transducer 111, and Positioning is performed so as to be positioned closer to the ultrasonic transducer 111.

  In step S4, echo data is acquired by all the groups 112 of the ultrasonic transducer 111. Specifically, the ultrasonic pulse transmission / reception timing setting means 122 sets the transmission / reception timing of the ultrasonic pulse. The ultrasonic pulse generator 123 excites the ultrasonic transducers 111 of all the groups 112 at the set timing. Each excited ultrasonic transducer | vibrator 111 transmits an ultrasonic beam toward the to-be-measured material 2a for 1st correction | amendment. Each ultrasonic transducer 111 receives an ultrasonic echo at the timing set by the ultrasonic pulse transmission / reception timing setting means 122.

  In step 5, the received ultrasonic echo is amplified by the ultrasonic echo receiving means 123, converted into a digital value by the A / D conversion means 124, and stored in the waveform storage means 125.

  In step 6, the arbitrary focus waveform synthesis unit 13 reads the echo received by the first group from the echo values stored in the waveform storage unit 125. Then, with respect to the ultrasonic beam received by the first group, the focal point is positioned on the bottom surface (the surface opposite to the surface facing the ultrasonic transducer 111) of the first correction target material 2a. An ultrasonic waveform is synthesized, and an echo of the synthesized ultrasonic waveform is calculated. The calculated echo is stored in the combined waveform storage unit 151 of the correction coefficient calculation unit 15.

  Next, the process returns from step S7 to step S3, and the alignment of the artificial flaw 21 is executed again. Here, the artificial flaw 21 formed on the first material to be measured 2a for correction is the second group of ultrasonic transducers 111 (that is, the 17th to 48th ultrasonic vibrations from one end of the array probe). Alignment is performed so that it is located on the center line of the ultrasonic beam synthesized in (child) and close to the ultrasonic transducer 111. This alignment is performed by rotating the first correction material to be measured by a predetermined angle after completing the operations from Step 3 to Step 6 for the first group.

  In step S4, echo data is acquired by all the groups 112 of the ultrasonic transducer 111. Specifically, since the operation is the same as described above, the description is omitted. In the description of the first group, “the first group of ultrasonic transducers 111” may be read as “the second group of ultrasonic transducers 111”.

  In step 5, the received ultrasonic echo is amplified by the ultrasonic echo receiving means 123, converted into a digital value by the A / D conversion means 124, and stored in the waveform storage means 125 in an accumulative manner.

  Hereinafter, the operations from step S3 to step S6 are repeated in the order of the third group, the fourth group,..., The seventh group of the ultrasonic transducer 111. When these operations are completed, the synthetic waveform storage unit 151 of the correction coefficient calculation unit 15 stores the artificial flaw 21 formed on the first correction target material 2a for all the groups 112 of the ultrasonic transducer 111. Will be stored cumulatively. Note that the relative positional relationship between the group 112 and the artificial flaw 21 is the same. That is, the artificial flaw 21 is located on the center line of the ultrasonic beam synthesized in each group 112 at a depth of ½ of the radius from the surface facing each ultrasonic transducer 111.

  Next, using the first correction target material 2a, an artificial flaw at a depth of 3/2 of the radius of the first correction target material 2a from the surface facing the ultrasonic transducer 111. 21, the echo is calculated and stored for each group 112 of the ultrasonic transducer 111.

  Specifically, it is as follows. First, in step S3, the artificial flaw 21 is aligned. That is, the first correction target material 2 a is rotated, and the artificial flaw 21 formed thereon is on the center line of the ultrasonic beam synthesized by the first group 112 of the ultrasonic transducer 111. In addition, these ultrasonic transducers 111 are positioned on the far side.

  Then, the operations from step S4 to step S6 are performed. Since this operation is as described above, a description thereof will be omitted. When the operations from step S3 to S6 are completed for the first group 112 of the ultrasonic transducer 111, the process returns from step S7 to step S2. Subsequently, the operation from step S3 to step S6 is performed for the second group 112 of the ultrasonic transducer 111. Since this series of operations is also as described above, a description thereof will be omitted.

  Hereinafter, the operations from step S3 to step S6 are repeated in the order of the third group, the fourth group,..., The seventh group of the ultrasonic transducer 111. When these operations are completed, the combined waveform storage unit 151 of the correction coefficient calculation unit 15 stores a depth of ½ of radius R (that is, 0.5R) from the surface for all the groups 112 of the ultrasonic transducer 111. And the echoes of the artificial flaw 21 at a depth of 3/2 of the radius (that is, 1.5R) are stored accumulatively.

  Next, the first correction target material 2a is removed from the ultrasonic flaw detector according to the embodiment of the present invention, and the second correction target material 2b is set. Since the artificial flaw 21 is formed in the center of the cross section of the second material to be measured 2b for correction, each group 112 of the ultrasonic transducer 111 and the artificial flaw 21 can be obtained without rotating the material to be measured 2b. The relative positional relationships of are all the same. Specifically, the artificial flaw 21 is on the center line of the ultrasonic beam synthesized by each group 112 of the ultrasonic transducer 111 and from the surface facing the ultrasonic transducer 111, its radius and It will be located at the same depth.

  Then, the operation from step S4 to step S6 is repeated for each group 112 of the ultrasonic transducer 111. As described above, since the positional relationship between each group 112 of the ultrasonic transducer 111 and the artificial flaw 21 is the same, it is necessary to align the artificial flaw 21 for each group 112 of the ultrasonic transducer 111 (step S3). Absent.

  When the operation using the second correction target material 2b is completed for all the groups 112 of the ultrasonic transducer 111, the combined waveform storage unit 151 of the correction coefficient calculation unit 15 stores the second correction target. The echoes of the artificial flaw 21 located at the depth equal to the radius from the surface of the material to be measured 2b facing the ultrasonic vibrator 111 and on the center line of the ultrasonic beam are further accumulated.

  Therefore, when the operations so far are completed, the combined waveform storage unit 151 of the correction coefficient calculation unit 15 stores all the groups 112 of the ultrasonic transducer 111 from the surface facing the ultrasonic transducer 111 for correction. Echoes are accumulated when the artificial flaw 21 is present at a depth ½ of the radius of the measured material 2a, a depth equal to the radius, and a depth of 3/2 of the radius.

  Table 1 below shows the echo height obtained for each group. Note that R represents the radius of the material to be measured 2 for correction.

  FIG. 7 shows the echo height of the artificial flaw 21 of each group and each depth when flaw detection is performed with a sensitivity that the echo height of the group 1 is 80% when the artificial flaw 21 is 1.0R deep. It is the graph which showed. If the reception sensitivity of the ultrasonic transducers 111 of each group 112 is equal, the echo height should be uniform for each depth. However, as shown in FIG. 7, the echo height actually differs between the groups 112. Specifically, the group 112 located near the center of the array-type probe 11 has a high sensitivity, and the group 112 located near the end tends to have a low sensitivity.

  Next, for each group of the ultrasonic transducer 111, the relationship between the distance from the surface of the correction target materials 2a and 2b or the time since the transmission of the ultrasonic beam and the echo height of the artificial flaw 21 is obtained. Create the graph shown. In these graphs, the domain (horizontal axis) is the distance from the surface or the time since the transmission of the ultrasonic beam, and the range (vertical axis) is the echo height. FIG. 8A is a graph showing the relationship between the distance from the surface and the echo height for the second group.

A function representing the relationship between the echo height and the distance from the surface of the measurement target materials 2a and 2b for correction or the time after transmitting the ultrasonic beam from the plot of the created graph, that is, the correction function Is estimated. For each group of this example, since the plots were smoothly connected to form a convex curve, the correction function F _i (x) was expressed by a quadratic polynomial of α _i x ² + β _i x + γ _i. Each coefficient and constants α _i , β _i , and γ _i were obtained by assuming that they are represented. Note that the subscript i indicates a function, coefficient, or constant of the i-th group of the ultrasonic transducer 111.

Next, G _i (x) = a / F _i (x) is defined. FIG. 8B is an example of a graph showing the value of 1 / F _i (x) for the second group (i = 2). When the correction function F _i (x) is multiplied by its reciprocal 1 / F _i (x), the value becomes approximately 1 regardless of the value of x, that is, the distance or time from the surface. Therefore, when the obtained echo height is multiplied by 1 / F _i (x), the echo height of the artificial flaw 21 becomes 100% regardless of the depth of the artificial flaw 21.

Next, the value of sensitivity coefficient a is set and multiplied by 1 / F _i (x) (that is, G _i (x) = a / F _i (x) is set). This sensitivity coefficient a is the echo height of the artificial flaw. Is a coefficient to adjust. In this embodiment, the sensitivity coefficient a is set to 0.8. That is, the echo height of an artificial flaw of φ0.3 mm is 80% of the transmitted ultrasonic beam regardless of the depth from the surface. Thus, the influence of the depth of the artificial flaw 21 is removed by multiplying the obtained echo height by the value of Gi (x).

  By performing such calculation for all the groups, the echo of the artificial flaw 21 becomes 80% regardless of the position in the depth direction in each group. FIG. 9 is a graph showing the results of the above calculations for all groups. As shown in FIG. 9, the echo height of the artificial flaw 21 of φ0.3 mm is 80% for all groups. That is, the sensitivity difference between groups is removed, and the sensitivity of each group can be made substantially equal.

  FIG. 10 is a graph showing a result of measuring a material to be measured with a flaw inside using the ultrasonic flaw detector according to the present embodiment, and an echo before correction of a block of a predetermined ultrasonic transducer 112. It is a graph which shows height, the correction coefficient computed for every block as mentioned above, and the echo height after correction | amendment (namely, the value which multiplied the correction coefficient to the echo height before correction | amendment). 10A shows the first block, FIG. 10B shows the fourth block, and FIG. 10C shows the seventh block.

  As shown in FIGS. 10A, 10B, and 10C, the measurement was performed in a state where the flaw was positioned on the center line of the ultrasonic beam transmitted from each block. Further, the first block and the second block in FIGS. 10A and 10B show the measurement results where the flaw is located on the side far from the ultrasonic transducer 111, and the seventh block in FIG. The block indicates a measurement result in which the flaw is located on the side close to the ultrasonic transducer 111.

  In the graph of the echo height before correction and the echo height after correction, the leftmost peak is a surface echo, the rightmost echo is a bottom echo, and the peak between them is a flaw echo.

  As described above, the ultrasonic transducer 111 group located near the center of the array-type probe has a high sensitivity, and the groups located at both ends tend to have a low sensitivity. Comparing FIG. 10 (a) and FIG. 10 (b), the same echo height should be obtained without correction. However, due to the above tendency, the result is that the echo height before correction is higher in the fourth group (a group located at the center) than in the first group (a group located at the end). Further, when FIG. 10B and FIG. 10C are compared, it is considered that the echo of a flaw far away from the surface is reduced due to the influence of attenuation or the like. The result is that the height is reversed.

  On the other hand, the echo height multiplied by the correction coefficient is independent of the group position of the ultrasonic transducer 111 and the depth of the flaw, as shown in FIGS. 10 (a), 10 (b), and 10 (c). If the flaws have the same shape and dimensions, the same echo height can be obtained. In this way, by multiplying the actual echo height (that is, sensitivity) by the correction coefficient calculated as described above, highly accurate measurement is performed regardless of the position of the ultrasonic transducer 111 and the depth of the flaw. Will be able to.

  As shown in the graph of each correction coefficient in FIG. 10, the correction coefficient may be different for each group of ultrasonic transducers 111. In other words, according to the above method, an optimal correction coefficient can be calculated according to the group of the ultrasonic transducers 111, and there is no difference in sensitivity between the groups, or small measurement with high accuracy can be performed. It becomes like this.

  Further, the diameter of the material to be measured to which the present invention can be applied is not limited to the diameter shown in the embodiment. FIG. 11 is a graph showing the echo height of each group of the ultrasonic transducer 111 for materials to be measured having various diameters. Except for the outer diameter of the material to be measured, the measurement conditions are the same as in the above example.

  As shown in FIG. 11, at any diameter, the group of ultrasonic transducers 111 located near the center of the array probe has a high echo height to be measured, and the groups at both ends have an echo height. There is a tendency to lower. This tendency is the same tendency as in the previous example. Therefore, it is considered that the present invention can be applied even when the outer diameters of the materials to be measured are different.

  While various embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments or examples, and various modifications can be made without departing from the spirit of the invention. Needless to say.

  For example, in the above-described embodiments and examples, the configuration in which the material to be measured is applied to a columnar body having a substantially circular cross section is shown, but the cross sectional shape of the material to be measured is not limited to a substantially circular shape. For example, the present invention can be applied to a material to be measured having an arbitrary cross-sectional shape such as an ellipse, another curved surface, or a polygon. In that case, the array-type probe may be shaped so as to face the surface of the material to be measured, and more preferably if the array-type probe is shaped so as to follow the surface of the material to be measured. Good.

  In the present embodiment, the correction coefficient is calculated using the correction target material 2. However, the correction coefficient is calculated by numerical calculation without using the actual correction target material 2. Also good. For example, a configuration may be used in which modeling of the material to be measured and measurement conditions described in the present embodiment is performed, a waveform is obtained by simulation using a finite element method, and a correction coefficient is calculated from the waveform data. With such a configuration, it is possible to save time and effort for preparing a correction target material on which artificial flaws (or artificial defects) are formed.

It is the block diagram which showed typically the structure of the ultrasonic flaw detector concerning 1st embodiment of this invention. It is the flowchart which showed the flow of operation | movement of the sensitivity correction method of the ultrasonic flaw detector concerning 1st embodiment of this invention. FIG. 3 is a schematic cross-sectional view showing the positional relationship between each block of the ultrasonic transducer and the artificial flaw formed on the correction target material in the sensitivity correction method for the ultrasonic flaw detector according to the first embodiment of the present invention. is there. It is the block diagram which showed typically the structure of the ultrasonic flaw detector concerning 2nd embodiment of this invention. It is the schematic diagram which showed the structure of the 1st example of the aligning means of the to-be-measured material used for correction | amendment used in the sensitivity correction method of the ultrasonic flaw detector concerning 2nd embodiment of this invention. It is the schematic diagram which showed the structure of the 2nd example of the aligning means of the to-be-measured material used for correction | amendment used in the sensitivity correction method of the ultrasonic flaw detector concerning 2nd embodiment of this invention. It is the graph which showed the echo of each artificial flaw of each group for every depth of the artificial flaw. (A) is the graph which showed the relationship between the position from the surface of an artificial flaw, and echo height, (b) is the graph which showed the reciprocal number of the correction coefficient computed based on (a). It is the graph which showed the sensitivity of each group after amendment. It is the graph which shows the echo height before correction | amendment of the block of each ultrasonic transducer | vibrator 112, the correction coefficient computed as mentioned above, and the echo height after correction | amendment, (a) is the 1st block, (b) is The fourth block (c) shows the seventh block. It is the graph which showed the echo height of each group of an ultrasonic transducer | vibrator about the to-be-measured material of various diameters.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Ultrasonic flaw detector 1b according to the first embodiment Ultrasonic flaw detector according to the second embodiment 11 Array probe 111 Ultrasonic transducer 112 Group of ultrasonic transducers 12 Signal processing unit 121 Ultrasonic pulse transmission / reception timing Setting means 122 Ultrasonic pulse generation means 123 Ultrasonic echo reception means 124 A / D conversion means 125 Waveform storage means 13 Arbitrary focus waveform synthesis section 14 Determination section 141 Signal correction means 142 Determination means 143 Output means 15 Correction coefficient calculation section 151 Synthesis Waveform storage means 152 Correction coefficient calculation means 153 Correction coefficient storage means 16 Control means 17 Positioning means 171 Cylinder 172 Piston 173 Rotating roller 174 Rotating power source 175 Holding part 191 Liquid layer 2a First material to be measured 2b for first correction Second correction target material 2c Third correction Measured material 21 artificial flaws 3 actual measured material

Claims (12)

"Dynamic focus method" ultrasonic flaw detector,
An array-type probe having a plurality of ultrasonic transducers arranged to face the surface of the material to be measured;
Waveform storage means capable of storing ultrasonic echoes received by each ultrasonic transducer for each ultrasonic transducer as waveform data;
An arbitrary focus waveform synthesizer that reads out the contents of the waveform storage means and is capable of phase synthesizing an ultrasonic beam having a focal point at an arbitrary position within a measurement range, and calculating an echo of the phase synthesized ultrasonic beam;
A correction coefficient calculation unit that calculates and stores a correction coefficient for multiplying the echo of the actual measured material;
A determination unit that determines the state of the actual measured material based on a value obtained by multiplying the echo calculated by the arbitrary waveform combining unit in the measurement of the actual measured material with the correction coefficient;
An ultrasonic flaw detector characterized by comprising:   The correction coefficient calculation unit uses a correction target material to be corrected for forming an artificial flaw of a predetermined shape and size at a predetermined depth from the surface with a correction coefficient for multiplying the echo of the actual target material to be measured. The ultrasonic flaw detector according to claim 1, wherein the ultrasonic flaw detector is calculated and stored based on the echo calculated by the arbitrary focal waveform synthesizer. The correction coefficient calculation unit is a combined waveform storage unit that stores an echo of an ultrasonic beam having a focus at a predetermined position calculated by the arbitrary focus waveform combining unit using the measurement target material for correction;
Correction coefficient calculation means for calculating a correction coefficient based on an echo stored in the combined waveform storage means and a coefficient for sensitivity adjustment set in advance;
Correction coefficient storage means for storing the correction coefficient calculated by the correction coefficient calculation means;
The ultrasonic flaw detector according to claim 2, comprising:   The ultrasonic flaw detection according to any one of claims 1 to 3, wherein the plurality of ultrasonic transducers arranged to face the surface of the material to be measured are arranged in an arc shape or an annular shape. apparatus.   The plurality of ultrasonic transducers arranged facing the surface of the material to be measured are grouped into a predetermined number of groups, and the correction coefficient calculation unit calculates and stores a correction coefficient for each group. The ultrasonic flaw detector according to any one of claims 1 to 4, wherein the ultrasonic flaw detector is provided.   The ultrasonic flaw detector according to claim 5, further comprising an alignment unit for the correction target material to be measured.   The correction coefficient calculation means phase-synthesizes the ultrasonic beam whose focal point is located at a predetermined position of the correction target material using the correction target material for each group. The echo height of the artificial flaw is calculated from the echo of the measured ultrasonic beam, and the depth of the artificial flaw from the surface of the material to be corrected and the echo height of the artificial flaw is calculated from the echo height of the artificial flaw. A function representing the relationship is estimated, a value obtained by multiplying an inverse of the estimated function by a coefficient for adjusting sensitivity is calculated, and the correction coefficient storage means stores the calculated value as a correction coefficient. Item 7. The ultrasonic flaw detector according to Item 5. A method for correcting the sensitivity of an ultrasonic flaw detector according to any one of claims 1 to 7,
A step of grouping a plurality of ultrasonic transducers provided in the array probe into a predetermined number of groups;
A correction material to be measured for forming artificial flaws having a predetermined shape and size at a predetermined depth from the surface is set in the ultrasonic flaw detector;
Phase-combining an ultrasonic beam having a focal point at a predetermined position of the correction target material for each group, and calculating an echo height of the artificial flaw from the echo of the phase-combined ultrasonic beam; ,
Estimating a function representing the relationship between the depth of the artificial flaw and the echo height of the artificial flaw based on the calculated echo of the ultrasonic beam;
Calculating a correction coefficient obtained by multiplying the inverse of the function by a coefficient for adjusting sensitivity;
Storing the correction coefficient;
A method for correcting the sensitivity of an ultrasonic flaw detector characterized by comprising: A method for correcting the sensitivity of an ultrasonic flaw detector according to any one of claims 1 to 7,
A step of grouping a plurality of ultrasonic transducers provided in the array probe into a predetermined number of groups;
A correction material to be measured for forming artificial flaws having a predetermined shape and size at a predetermined depth from the surface is set in the ultrasonic flaw detector;
Phase-combining an ultrasonic beam having a focal point at a predetermined position of the correction target material for each group and calculating an echo height of the artificial flaw from the echo of the phase-combined ultrasonic beam; ,
Estimating a function representing the relationship between the depth of the artificial flaw and the echo height of the artificial flaw based on the calculated echo of the ultrasonic beam;
Storing a function representing a relationship between echo heights of the artificial flaws;
A method for correcting the sensitivity of an ultrasonic flaw detector characterized by comprising:   The shape and size of the artificial flaw formed on the measurement target material for correction is the minimum shape and size that should be judged as a “defect” when existing in the actual measurement target material. 10. The sensitivity correction method for an ultrasonic flaw detector according to 9.   The correction target material is a cylindrical member having a circular cross section, and the artificial flaw is formed at a position half the radius of the correction target material from the center, and the correction target material Is rotated 180 ° to calculate the echo height of the artificial flaw located at a half depth of the radius from the surface and the echo height of the artificial flaw located at a depth of 3/2 of the radius from the surface. The method for correcting a sensitivity of an ultrasonic flaw detector according to any one of claims 8 to 10, wherein: An ultrasonic flaw detection method using an ultrasonic flaw detector whose sensitivity is corrected by the sensitivity correction method of the ultrasonic flaw detector according to claim 9 or 10,
Comparing the echo height of the flaw present in the actual measured material with the echo height of the artificial flaw of the stored measured material for correction;
A step of determining a defect existing in the actual material to be measured as a defect when an echo height existing in the actual material to be measured is higher than an echo height of the artificial defect of the stored measurement material to be corrected; ,
The ultrasonic flaw detection method characterized by having.

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